Experimental Realization of a Casimir Diode: Non-reciprocal Energy Transfer by Casimir Force

The Casimir effect is essential for micro- and nanotechnologies because it is inevitably huge at a small separation. The Casimir interaction has been used to realize various advanced function. However, a non-reciprocal Casimir device is still unexplored. In this chapter, we will introduce our recent realization of non-reciprocal energy transfer between two micro-mechanical oscillators by Casimir effect. We will first show how we realize a strong coupling and energy transfer by the parametric coupling scheme. This will be followed by a measurement of the exceptional point in the parameter space by a careful design. We will then present the results of non-reciprocal energy transfer by dynamically driving the system near the exceptional point. In the last section of this chapter, we will show detailed derivations of the effective system Hamiltonian and the exceptional point. Parts of the contents in this chapter have been published in Xu et al. (Nat Nanotechnol 17(2):148–152, 2022).